1. Field of the Invention
The present invention relates to articulated arm transfer devices.
2. Description of the Related Art
The transfer of delicate silicon wafers or the like between a plurality of work stations or locations in the manufacture of semiconductor devices presents unique handling problems. The silicon wafers are very delicate and have highly polished surfaces. When the wafers are abruptly moved, they tend to slide. This sliding action can cause the silicon wafers to abrade or alternatively can cause damage to their edges if they collide.
There are numerous devices described in the prior art for transferring silicon wafers. Some examples are given in U.S. Pat. No. 5,180,176. In particular, U.S. Pat. Nos. 4,666,366 and 4,909,701 disclose wafer transfer handling apparatus having an articulated arm assembly which extends and retracts in a "froglike" motion to transfer an object such as a wafer between a plurality of locations. Two articulated arms are operatively coupled such that when one arm is driven by a motor the articulated arms extend and retract in a "froglike" or "frogkick" type of motion. A platform is coupled to the arms and has the object to be transferred disposed thereon.
As the size of substrates (such as, for example, flat-panel TV screens) becomes larger, the size of the robots used in their fabrication becomes larger also, and the prior practice of raising the whole robot to effect the pick-up of the substrate requires excessive power and time.